Scientists find rare shrimp in Lake County river

Shrimp normally found in southern and central Illinois or further south

February 06, 2013|By Lisa Kirschner, Special to the Tribune

Glass shrimp, which are very rare, were found in the Des Plaines River and identified by the Lake County Forest Preserves. (Provided, Simon Helgeson)

It's not every day scientists see something they haven't before, but that's exactly what happened to some Lake County Forest Preserves employees recently.

The forest preserves' natural resource manager, Jim Anderson, and his team discovered during routine sampling of the Des Plaines River a species of shrimp not normally found in northeastern Illinois.

This type of shrimp — known as "Palaemonetes kadiakensis," glass shrimp or Mississippi grass shrimp — is normally found only in southern and central Illinois or other areas further south, according to Anderson. The shrimp was collected during an annual aquatic survey conducted by Anderson's staff in Lake County.

"(A staff member) brought the specimens to me and was inquiring what they were because he had not seen them before," Anderson wrote in an email. "I immediately recalled that they were grass shrimp since I studied aquatic streams and invertebrates in college."

The shrimp were found near one of the low dams in the river in August and were brought back to the Lake County Forest Preserves district office. Anderson said official identifications of species typically take place during winter months. The shrimp was officially identified as Palaemonetes kadiakensis late last month.

According to Anderson, the glass shrimp feeds on vegetation in streams and is about an inch long with a tail, whip-like antennas and two small black eyes.

This is the first time glass shrimp have been found in Lake County, Anderson said, but they have been spotted in Otter Creek in Kane County and in the Kankakee River in Kankakee County.

"It's a good indicator of water quality," Anderson said. "We use an index to determine the quality of the stream. It is called the 'index of biological integrity,' which places values on the type of species collected and their tolerance to poor or good water quality. This lets us compare different years of collection and make a determination of improving or worsening conditions."

The presence of the Palaemonetes kadiakensis may be an indication that stormwater management practices are improving water quality in county rivers, streams, lakes and creeks, according to Anderson. Climate change may also be a factor, he said, but this has not been investigated.

Stephen Pescitelli, a scientist at the Illinois Department of Natural Resources, agrees. He also thinks the species has probably been living this far north for quite some time.

"It probably hasn't magically appeared in this area," said Pescitelli. "We happened to be lucky to come across it, but it's a bit exciting whenever you find a new critter. There have been a lot of restoration efforts at increasing and preserving wetlands over the years, so that's probably helped this little guy."

The Illinois Natural History Survey helps to track where and when different species of fish and crustaceans appear in the state's rivers, streams, creeks and other waterways. Chris Taylor, curator of fishes and crustaceans at the Illinois Natural History Survey's Prairie Research Institute, also said the glass shrimp's discovery so far north was a rare one.

"This is unusual in that it is one of a very few species of shrimps that live in freshwater habitats of North America," said Taylor in an interview conducted via email. "Hundreds of species of shrimp live in the world's oceans, but only five have successfully colonized the fresh waters of the United States. (This shrimp) is also unique in that it has adapted to the very cool temperate climates and lives further north than any of the other freshwater shrimp found in North America."

Anderson said his team will be on the lookout for more glass shrimp during their next annual collection period.